1. Field of the Invention
The present invention relates to a method for filtering packets in a wireless network system, and more particularly, to a method for filtering the packets by using the address code of a network interface card in the packet.
2. Description of the Prior Art
In recent years, along with the fast development of wireless networks, many significant data are being delivered through the networks. Therefore, safety and network transmission speed are increasingly important issues.
The safety protection in the network of the prior art is mainly achieved through the encryption of the IEEE 802.11 wired equivalent privacy (WEP) protocol. That is, the same set of WEP keys will be used from the user client to the access point to encrypt the document, and the encrypted document can be transmitted through the network system.
Please refer to FIG. 1. FIG. 1 is a schematic diagram showing the transmission of a document 12 by a WEP key system 10 of the prior art. A first port 18 of the WEP key system 10 comprises an encryption module 14 for encrypting the document, and a decryption module 16 for decrypting the document. A second port 28 of the WEP key system 10 also comprises an encryption module 24 and a decryption module 26. When a user would like to deliver the document 12 from the first port 18 to the second port 28 and to conceal the contents of the document from a third party, the user can make use of the WEP key system 10 to secretly transmit the document 12. The instructions of the secret transmission by the WEP key system 10 are described as follows: the user first makes use of the encryption module 14 to encrypt the document 12 to a ciphered text 20 with a WEP key, then the user can make use of a public gateway 19 to transmit the ciphered text 20 to the second port 28. When the ciphered text 20 is transmitted to the second port 28, the decryption module 26 will decrypt the ciphered text 20 with the WEP key. Afterwards, the user at the second port 28 can realize the contents of the document 12. Likewise, when the user at the first port 18 receives the ciphered text transmitted from the second port 28 and encrypted with the WEP key, the user can make use of the decryption module 16 to decrypt the ciphered text with the WEP key. In the process of transmission of the ciphered text, if a hacker in the network would like to cut and take the ciphered text 20, the hacker cannot readout the concealed contents of the ciphered text 20 whether the hacker obtains the ciphered text 20 or not since the hacker does not have the WEP key. Therefore, the WEP key system 10 can provide the function of secretly delivering documents.
However, the WEP key system 10 contains at least the following three defects:
1) The administrator of the network has to carry the WEP key to a plurality of computers to set the secret codes, and the procedure wastes time and manpower and easily lets the WEP key be stolen or lost.
2) If the administrator would like to shorten the setting time, a multi-user secret-code-setting task can be performed at the same time. However, the secret code will be revealed to many people, and will not be concealed.
3) The document-secrecy-method with the WEP key is to encrypt each of the transmitted documents and to decrypt each of the received documents. Since the value of the WEP key is usually very big(128 bits), the tasks of encryption and decryption usually consume a lot of time.